Overview of hybrid membranes for direct-methanol fuel-cell applications

Ahmad, Hasan; Kamarudin, Siti Kartom; Hasran, Umi Azmah; Daud, Wan Ramli Wan

doi:10.1016/j.ijhydene.2009.12.054

Cited by 230 publications

(88 citation statements)

References 93 publications

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“…However, breaking out from the niche market requires improvements in the performance, durability and cost of the catalysts [1] and membranes [2]. A crucial limitation of the DMFC is the catalysis of the methanol oxidation reaction at the anode.…”

Section: Introductionmentioning

confidence: 99%

The effect of Nafion content in a graphitized carbon nanofiber-based anode for the direct methanol fuel cell

Kanninen

Borghei

Ruiz

et al. 2012

International Journal of Hydrogen Energy

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The performance and stability of a direct methanol fuel cell (DMFC) with membrane electrode assemblies (MEA) using different Nafion ® contents (30, 50 and 70 wt % or MEA30, MEA50 and MEA70, respectively) and graphitized carbon nanofiber (GNF) supported PtRu catalyst at the anode was investigated by a constant current measurement of 9 days (230 h) in a DMFC and characterization with various techniques before and after this measurement. Of the pristine MEAs, MEA50 reached the highest power and current densities. During the 9-day measurement at a constant current, the performance of MEA30 decreased the most (-124 µV h -1 ), while the MEA50 was almost stable (-11 µV h -1 ) and performance of MEA70 improved (+115 µV h -1 ). After the measurement, the MEA50 remained the best MEA in terms of performance. The optimum anode Nafion content for commercial Vulcan carbon black supported PtRu catalysts is between 20 and 40 wt %, so the GNF-supported catalyst requires more Nafion to reach its peak power. This difference is explained by the tubular geometry of the catalyst support, which requires more Nafion to form a penetrating proton conductive network than the spherical Vulcan.Mass transfer limitations are mitigated by the porous 3D structure of the GNF catalyst layer and possible changes in the compact Nafion filled catalyst layers during constant current production.2

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Section: Introductionmentioning

confidence: 99%

The effect of Nafion content in a graphitized carbon nanofiber-based anode for the direct methanol fuel cell

Kanninen

Borghei

Ruiz

et al. 2012

International Journal of Hydrogen Energy

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“…Although proton conductivity is normally lower for chitosan as compared to Nafion ® , 8,10 the thin LbL film of chitosan/PVS deposited onto the Nafion ® membrane film hardly contributes to enhancing the resistance corresponding to proton transport. Figure 6a shows the cyclic voltammetry experiments for the Pt electrode in the presence of several different methanol concentrations, in 0.5 mol L -1 H 2 SO 4 . Current values were normalized by the area of exposed platinum (0.246 cm 2 ), which was calculated from the coulometric charge of hydrogen desorption.…”

Section: Resultsmentioning

confidence: 99%

“…Nafion ® is the membrane that is normally employed as PEM for DMFCs due to its high chemical stability and proton conductivity. 4 However, novel materials have also been prepared and tested as PEM for DMFCs once Nafion ® gives rise to large methanol crossover. [5][6][7] Chitosan is the deacetylated form of chitin, a polysaccharide present in the shells of crabs and in the exoskeleton of shrimps, and can be used as a PEM for DMFCs.…”

Section: Introductionmentioning

confidence: 99%

Self-assembled films from chitosan and poly(vinyl sulfonic acid) on Nafion® for direct methanol fuel cell

Vinhola¹,

Facci²,

Dias³

et al. 2012

J. Braz. Chem. Soc.

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Filmes de quitosana/poli(ácido vinilsulfônico) (PVS) foram depositados sobre membranas de Nafion ® a partir do método camada por camada (LbL), visando o seu uso em células a combustível de metanol direto (DMFC). Métodos computacionais e espectros de infravermelho com transformada de Fourier (FTIR) sugerem a formação de um par iônico entre o grupo sulfônico do PVS e o grupo amino protonado da quitosana, o qual promove o crescimento dos filmes LbL sobre a membrana de Nafion ® , assim como impede parcialmente a passagem de metanol. Experimentos de cronopotenciometria e varredura linear de potencial foram realizados a fim de se investigar a passagem de metanol através das membranas de Nafion ® e quitosana/PVS/Nafion ® em uma célula a diafragma. Os valores de resistência iônica associada ao transporte de prótons nas membranas de Nafion ® e quitosana/PVS/Nafion ® são próximos, de acordo com as medidas de impedância elétrica devido à pequena espessura do filme LbL. Assim, espera-se um melhor desempenho da DMFC, uma vez que a resistência do filme automontado é insignificante comparada ao resultado associado à passagem de metanol através das membranas.Chitosan/poly(vinyl sulfonic acid) (PVS) films have been prepared on Nafion ® membranes by the layer-by-layer (LbL) method for use in direct methanol fuel cell (DMFC). Computational methods and Fourier transform infrared (FTIR) spectra suggest that an ionic pair is formed between the sulfonic group of PVS and the protonated amine group of chitosan, thereby promoting the growth of LbL films on the Nafion ® membrane as well as partial blocking of methanol. Chronopotentiometry and potential linear scanning experiments have been carried out for investigation of methanol crossover through the Nafion ® and chitosan/PVS/Nafion ® membranes in a diaphragm diffusion cell. On the basis of electrical impedance measurements, the values of proton resistance of the Nafion ® and chitosan/PVS/Nafion ® membranes are close due to the small thickness of the LbL film. Thus, it is expected an improved DMFC performance once the additional resistance of the self-assembled film is negligible compared to the result associated with the decrease in the crossover effect.Keywords: chitosan, direct methanol fuel cell, proton exchange membrane, crossover effect, methanol permeability IntroductionDirect methanol fuel cells (DMFCs) are the most promising portable, stationary power sources with application in several fields. In these cells, methanol and air are continually injected into the anode and cathode compartments, respectively, thus providing energy with high efficiency. Methanol has been largely employed as fuel once it is abundant and inexpensive. Even though DMFCs produce carbon dioxide, which is released into the atmosphere, their high efficiency guarantees low pollution as compared to other power sources. [1][2][3] One drawback of DMFCs is the so-called crossover effect, through which methanol leaves the anodic compartment and crosses the proton exchange membrane (PEM), thereby promoting cell de...

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“…But the fillers (ceramic and protonic conductors) create tortous path ways for the molecular transportation, reduces the electro osmotic drag which effectively dries the membrane at the anode side and suppresses the flooding. It has been observed that the cross over current measured with the modified membrane in an order of magnitude lower than that of the unmodified polymer membranes (Ahmad et al 2010;). …”

Section: Fuel Cross Overmentioning

confidence: 99%